I took the top grill off and of course there was disintegrated foam everywhere. I cleaned the top grill and fixed the actual grill a little (it was pushed in).
The capsule has this little black plastic basket that protects it. It comes off by undoing the two little screws on the perimeter of the capsule. Be careful to not drop the screw driver into the capsule, though. I didn’t take a picture with the basket on, and I also started cleaning the capsule before taking pictures, but here’s the capsule with quite a bit of dirt still, and the basket before cleaning it.
A guy I talked to through the TapeOp messageboard said that he didn’t have to clean the capsule too hard to get the bass reponse back. I tested it in the condition shown above, but I still got no bass. So I kept cleaning.
At first I was cleaning with a q-tip dipped in 99% isopropyl alcohol. It worked, but I was told that the q-tip is a little too rough for the delicate membrane. So I switched to a fine artist’s brush dipped in 99% IPA. That worked well and it was better for when cleaning around the tiny coil wires or getting into the crevices. Also, the IPA is only necessary for getting the gunk loose. It can be brush off with a dry brush, and remember to brush towards the outside, away from the center.
There are still some specks of dirt under the membrane, but now the bass response was back. Check it out. I don’t have a very boomy voice, but for comparison, you can check my friend trying out the microphone on his voice prior to handing it to me.
At this point I was ready to move ahead and order new foam, clean the whole thing and work on the wiring (low cut switch is not working). However, if you’ve spent any time reading about these microphones and the ways in which they become dysfunctional, you probably saw mentions of “baby rattle”. There are examples of it online, but basically the rattle is there when the microphone is used on low end sources with fast transients. So I decide to test it on bass, and sure enough, with some low notes that were loud enough, there was this rattle that almost sounded like static. Here’s what it sounded like.
Honestly, I don’t know if that qualifies as baby rattle, because baby rattle is the result of the pole piece being loose, and this one is not loose. I also noticed that the buzzing is still there, although to a lesser extent, when the microphone is facing away from the speaker cabinet.
I asked a friend who worked on a couple of RE20s about it, and he said that he had one with a similar problem and he believed that it was dirt dirt in the motor and that some notes would make it resonate against the coil. Whether this is the problem, or it is a variant of the baby rattle or another pole piece related problem, this is the end of the road for me. I do not know how to remove the membrane, I do not have the tools to do it, and I don’t think the owner of the microphone will want to pay to learn how to do all this on his microphone. So I contacted Ben at MicDaddy.com. He’s universally recommended for fixing EV microphones and his rates are supposed to be lower than EV’s. I still haven’t heard from him, so I don’t know what are his rates yet. If he’s too expensive, the owner of the microphone said that he’ll have me replace the foam, and then the microphone at least will be usable on voice.